The clownfish is a brightly colored omnivorous fish found in the Pacific and Indian Oceans. The vivid coloration, resembling the bright face paint worn by circus clowns, accounts for its name. There are 30 different species of clownfish, and most are known for their successful symbiotic relationship with the poisonous sea anemone. Their beauty makes them sought-after aquarium fish, although they can be difficult to care for as pets. In the early 2000s, these fish were well known for their portrayal in the film Finding Nemo.

The most widely recognized varieties of clownfish are bright orange, with wide white vertical stripes and thin black stripes. Other varieties can be black, green, or red; most have the distinctive white striping. They range in size from 3 to 7 inches (10 to 18 cm) long. They subsist on algae, plankton, and smaller fish and sea creatures. Some of the creatures in their diet could otherwise pose threats to the sea anemones that they live in.

The relationship of the clownfish to the sea anemone is a classic example of symbiosis, which is mutually beneficial cooperation between two unlike species. The anemone is a stationary creature with poisonous tentacles that lives anchored to the ocean floor or another underwater surface. The clownfish is immune to the anemone’s poison and shelters within the creature’s tentacles for protection from predators. In return, the fish not only protects the anemone from potential threats, but also nourishes the anemone with its bodily wastes.

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Clownfish are serial hermaphrodites. They are all are born male, and these males will cluster in a group near or within their host anemone. The largest and most dominant fish will transform into a female and breed with one of the males. If the female dies or is captured, this male becomes the dominant female in turn. Clownfish are popular aquarium pets, but may not exhibit their unique sex and symbiotic behavior in captivity. Those captured in the wild do not adapt well to aquaria and have a high fatality rate.

The title character in the 2003 animated film Finding Nemo was a clownfish, as was the movie’s main character. Ironically, however, the film’s worldwide success led to increased demand for these fish as pets, with a negative impact on populations in the wild. Conversely, some sympathetic Finding Nemo fans released their fish into the Atlantic Ocean, with equally catastrophic results. People seeking exotic aquarium pets should consult with an expert in tropical species first.

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